EP3966168A1

EP3966168A1 - Device for treating water with ultraviolet radiation in a purification plant open channel

Info

Publication number: EP3966168A1
Application number: EP20723407.1A
Authority: EP
Inventors: Pierre Jean Vialle; Patrick BORDAS; André Bordas; Antoine AUBRUN; Alexandre PESTOURIE
Original assignee: UV Germi SA
Current assignee: UV Germi SA
Priority date: 2019-05-07
Filing date: 2020-05-05
Publication date: 2022-03-16
Also published as: FR3095814A1; FR3095814B1; WO2020225260A1

Abstract

A device (100) for treating fluid with ultraviolet radiation in a purification plant open channel, comprising a plurality of ultraviolet tubes (10), each one consisting of an ultraviolet lamp (11) placed in a protective sheath (12), a body (20) in which said tubes are installed parallel to one another, a system for cleaning the protective sheaths, an electrical unit (40) and an auxiliary unit (50) containing a cleaning product reservoir; the ultraviolet tubes (10) are arranged inclined relative to a horizontal direction of fluid flow, and the cleaning system comprises a photocatalytic media in contact with the protective sheaths.

Description

Device for treating water by ultraviolet radiation in the open channel of a wastewater treatment plant

TECHNICAL AREA

The present invention belongs to the general field of the treatment of fluids, in particular systems for disinfection by ultraviolet radiation, commonly referred to as “UV reactors”, and relates more particularly to a device for the treatment of water by ultraviolet radiation in an open channel of a wastewater treatment plant. .

STATE OF THE ART

No need to recall that the management of water as a resource is a major and primordial issue in our societies, even sometimes critical in certain regions of the world. The use of water, whether domestic or industrial, often requires prior treatments such as filtration, disinfection, chlorination and sterilization, in order to make water potable, for consumption, or simply safe for any other use or release into the environment. These treatments can be carried out in various ways involving different physical and biophysical phenomena such as the destruction of microorganisms by radiation with strong ionizing power, sufficient to deactivate microorganisms by stopping their multiplication, or even to completely annihilate them.

To this end, it is known and customary to treat water by ultraviolet radiation in order to eliminate both bacteria and viruses without generating any toxic product or even modifying the organoleptic properties of the treated water. The principle consists in using the sterilizing and germicidal action of a part of the ultraviolet radiation called UV-C, corresponding to a conventional interval of wavelengths between 280 and 100 nm (the shortest of UV spectrum), and characterized by the most energetic UV rays. These UV-Cs are generated artificially by lamps used in UV reactors, which can have different shapes and sizes depending on the intended application.

UV disinfection is a technology that has proven itself in terms of safety, reliability, efficiency and economic benefits over the years. For example, more than 15% of wastewater treatment plants in North America currently use UV disinfection as the primary method of disinfection.

Examples of UV reactors are described in documents CN107200380A, US2002162969A1, US2013153515A1, KR101308426B1,

CA2526060A1 and CA2668593A1.

The well-mastered UV disinfection process finds applications in several fields, in particular the treatment of water and more particularly of wastewater at the outlet of purification stations.

It is known practice to install UV reactors at the outlet of purification stations to treat wastewater before it is reused or rejected. In this case, the reactors are said to be in open channel, unlike the so-called closed UV reactors whose most widespread application is the treatment of drinking water, and crossed by water between an inlet section and an outlet section delimiting an effective treatment area. Open channel UV reactors are mainly used in municipal water / wastewater treatment plants for water recycling and reduction of pollutant drainage into the environment.

Documents CA2526060A1 and US2008044320A1 describe open channel UV reactors.

In these reactors, the UV lamps are arranged either parallel to the direction of flow of the fluid or perpendicular to it.

The water flows in this type of installation are generally high and require the use of several UV reactors arranged in modules, each reactor having several UV lamps (several dozen in some reactors). As a result, the maintenance of this type of installation becomes more critical.

Indeed, due to prolonged immersion in polluted water, mineral and / or organic deposits form on the protective sheaths of the UV lamps, usually made of quartz, and have the effect of altering the efficiency of the reactor by blocking (by absorbing) part of the ultraviolet radiation.

The cleaning of the protective sheaths of the lamps in UV reactors is a problem known in the art, some reactors incorporate automated cleaning devices generally comprising cleaning members, such as rotating brushes, the mechanical action of which makes it possible to clean the surfaces of the ducts. Document CN107200380A describes this type of cleaning.

Other UV reactors incorporate chemical cleanings based on surfactant additives alone or mixed in situ with high pressure water jets or compressed air. Document US2005023482A1 describes such a chemical cleaning.

The aforementioned mechanical and chemical solutions can be combined to improve the efficiency of cleaning as in the UV reactor described in document CA2668593A1 and which comprises a hybrid cleaning system by water, air or gas flow with the use detergents and by mechanical means such as wipers.

There are also UV reactors with ultrasonic cleaning of the sheaths, the induced ultrasonic vibrations making it possible to interrupt the scaling of the reactor components, as described in document WO9927972A1.

Document CN107827201A discloses, for example, a UV reactor comprising quartz sheaths, the outer walls of which are coated with a superhydrophobic layer to limit the deposits of aqueous or suspended pollutants in water.

However, the effectiveness of these solutions remains limited and does not exempt users from frequent maintenance of their UV reactors.

PRESENTATION OF THE INVENTION

The main aim of the present invention is to overcome the limitations of the prior art by proposing a UV reactor which has reduced bulk, by an innovative compact arrangement of the UV lamps, and an automated physicochemical cleaning system of improved efficiency. To this end, the present invention relates to a device for treating fluid by ultraviolet radiation in the open channel of a wastewater treatment plant, comprising a plurality of ultraviolet tubes, each consisting of an ultraviolet lamp placed in a protective sheath, a body in which said tubes are installed parallel to each other, a system for cleaning the protective sheaths, an electrical unit and an auxiliary unit containing a tank for cleaning product This device is remarkable in that the ultraviolet tubes are arranged so inclined with respect to a horizontal direction of fluid flow, and in that the cleaning system comprises photocatalytic media in contact with the protective sleeves.

According to a particularly advantageous embodiment, the body has a parallelepiped shape and comprises a base extended along a longitudinal axis of the device, two uprights, an upstream upright and a downstream upright, perpendicular to the base, and two sidewalls, each side comprising a couple triangular plates spaced apart, placed at two opposite angles of said side so as to define an opening parallel to the UV tubes.

More particularly, each upright comprises two parallel and spaced bars defining openings corresponding to a fluid inlet at the level of the upstream upright and to a fluid outlet at the level of the downstream upright, the ultraviolet tubes being entirely contained in a delimited treatment volume. by said inlet and outlet and the base.

Advantageously, the upstream upright comprises two adjustable joints, each being placed along a bar of said upright, to sealingly connect the inlet of the treatment device and the walls of the sewage treatment plant channel.

According to one embodiment, the ultraviolet lamps are mercury vapor and produce monochromatic UV-C radiation, and the protective sheaths are made of quartz, the quartz having a high transmittance of the radiated wavelengths.

Advantageously, the cleaning system comprises cleaning rings, each being placed around an ultraviolet tube and provided with a part supplied with the cleaning product and a part supporting a photocatalytic medium. More particularly, the cleaning system comprises several cleaning assemblies, each of said assemblies comprising several integral cleaning rings. The rings of a cleaning assembly can for example be juxtaposed and connected by a plate.

For example, photocatalytic media are based on titanium dioxide.

Advantageously, the cleaning system is mounted to slide along the ultraviolet tubes, driven by a mechanism comprising a gear motor.

In addition, the body has gripping means for lifting and moving the device.

Advantageously, the inclination of the body of the treatment device is adjustable by a means bearing on a bottom of the sewage treatment plant channel, such as a wedge, so as to vary the height covered by the radiation from the tubes. ultraviolet (10), to match the height of the fluid in the channel.

The fundamental concepts of the invention having just been explained above in their most elementary form, other details and characteristics will emerge more clearly on reading the following description and with reference to the accompanying drawings, giving by way of nonlimiting example an embodiment of a treatment device in accordance with the principles of the invention.

BRIEF DESCRIPTION OF THE FIGURES

Figures and elements of the same figure are not necessarily to the same scale. In all the figures, identical or equivalent elements bear the same reference numeral.

It is thus illustrated in:

[Figure 1]: a perspective view of the device for treatment by ultraviolet radiation according to a first embodiment of the invention;

[Figure 2]: a detail of Figure 1 showing the arrangement of part of the cleaning system for the protective sheaths of ultraviolet lamps;

[Figure 3]: a partial perspective view of the treatment device with the cover of the electrical unit open;

[Figure 4]: a perspective view of the device for treatment by ultraviolet radiation according to a second embodiment of the invention; [Figure 5]: a front view of the treatment device showing adjustment joints at the level of the upstream post.

DETAILED DESCRIPTION OF EMBODIMENTS

The terminology used in the present description should in no case be interpreted in a limiting or restrictive manner. It is simply used in conjunction with a detailed description of certain embodiments of the invention.

In the embodiment described below, reference is made to a device for treating water by ultraviolet radiation intended mainly for purification stations. This non-limiting example is given for a better understanding of the invention and does not exclude the installation of said device in other environments.

In the remainder of the description, the expression “UV reactor” is used laconically to denote, according to a common meaning in the field of water treatment, a device for the essentially bactericidal treatment of water or other fluids by ultraviolet radiation.

Figure 1 shows a UV reactor 100 according to the invention mainly comprising a plurality of ultraviolet tubes 10, a support body 20 in which said tubes are mounted, a cleaning system (30, 35) of the ultraviolet tubes, an electrical unit 40, for a motorization of the cleaning system and an electrical connection of the ultraviolet tubes, and an auxiliary unit 50 making it possible, among other things, to store a cleaning chemical.

According to current use, the UV reactor 100 is connected to a control and power part placed in a remote cabinet, not shown, of the programmable logic controller type for example.

The ultraviolet tubes 10 are parallel and arranged inclined with respect to a horizontal plane (XY). According to the illustrated embodiment, the ultraviolet tubes 10 are arranged in superimposed rows, each row comprising a determined number of tubes.

Each ultraviolet tube 10 consists of an ultraviolet lamp 11 placed, coaxially, inside a tubular and transparent protective sheath 12. Ultraviolet lamps 11 produce ultraviolet radiation suitable for the targeted bactericidal and germicidal treatments and are for example low-pressure (LP) amalgam lamps and / or medium-pressure (MP) mercury vapor lamps, preferably amalgam lamps. BP producing monochromatic UV-C ultraviolet radiation with a wavelength of 254 nm, more precisely 253.7 nm, close to a germicidal sensitivity peak (265 nm) for microorganisms such as bacteria, viruses and mainly protozoa .

Each ultraviolet lamp 11 is placed in a protective sheath 12 which protects it from environmental attacks and insulates it electrically and thermally from water.

The protective sheaths 12 have a cylindrical shape with a circular base and dimensions suitable for receiving the lamps 11. In other words, the sheaths 12 have an internal diameter substantially greater than that of the lamps 11, to allow the insertion and the sliding of the lamps. the latter, and a length extending at least over the entire radiating part of the lamps 11. The protective sheaths 12 are made of a transparent material, at least at the wavelengths of the ultraviolet radiation emitted by the lamps 11, such as quartz which is characterized by its high transmittance for the radiated wavelengths.

The body 20, according to the illustrated embodiment, has a generally parallelepipedal shape resulting from an assembly of bars and plates, and comprises a horizontal base 21, two vertical uprights, upstream 22a and downstream 22b according to the direction of flow. of a fluid passing through the UV reactor 100, and an upper cross member making it possible to support the units 40 and 50. The base 21 constitutes the element by which the UV reactor 100 rests on the ground, or on any other horizontal or slightly inclined surface of a sewage treatment plant channel for example, and has a rectangular shape with two opposite sides, preferably transverse, are surmounted by uprights 22a and 22b. The uprights, upstream 22a and downstream 22b, each consist of two spaced vertical bars respectively defining an inlet E and an outlet S of the fluid. The body 20 further comprises two facing plates 23, each of said plates being arranged diagonally at the level of a lateral face of the body 20, adjacent to the inlet E and the outlet S. The plates 23 extend along the ultraviolet tubes 10 and cover them laterally. Longitudinal slots are made in each plate 23 in order to facilitate the flow and transfer of the fluid passing through the UV reactor 100.

The structure of the body 20 can thus be assimilated to a triangulated assembly, or lattice, at the level of each lateral face of said body, in which horizontal and vertical bars and diagonal plates define two pyramidal volumes on one side and on the other side. another of the ultraviolet tubes 10 and between the inlet E and the outlet S. As a result, these two volumes constitute useful treatment volumes in which the ultraviolet radiation of the tubes 10 is concentrated.

Incidentally, the body 20 is provided with a ramp 24 at the level of the inlet E disposed between the diagonal plates 23 and having a sufficient length to cover the lower ends of the ultraviolet tubes 10 which do not constitute radiating surfaces, and to avoid thereby a less effective contact between the passing fluid and said ends.

The body 20 is therefore characterized by its incomplete design opposing a minimum of obstacles to the flow of the fluid, and the ultraviolet tubes 10 are characterized by their inclined arrangement within the structure of said body which makes it possible to optimize the treatment of the fluid. fluid passing through with respect to the horizontal or vertical tubes of the prior art by maximizing the effective treatment sections, sections which correspond to the projections of the straight flow sections on the upper and lower faces of the set of ultraviolet tubes 10. De more, for the same useful length of the UV reactor, the diagonal arrangement is that which allows the installation of the tubes of greater length.

The UV reactor 100, according to the embodiment of FIG. 1, is characterized by largely stripped side faces which make it more suitable for operation as a module in a battery of UV reactors side by side over the entire width of the reactor. a wastewater treatment plant channel, so as to avoid the formation of dead flow zones between two successive reactors, zones in which the fluid would not be reached by the ultraviolet radiation from the lamps. Such dead zones can, for example, form in the case of reactors with full or almost full side faces preventing the ultraviolet radiation of the lamps from reaching the leaking fluid between two side faces placed side by side, each belonging to a different UV reactor.

Alternatively, the UV reactor 100 according to the exemplary embodiment of Figures 4 and 5 is more suitable for operating alone in a sewage treatment plant channel having a width substantially equal to the thickness of said reactor.

To adapt to the width of the channel, the UV reactor 100 has on its upstream upright 22a two adjustable joints 221, one joint along each longitudinal side of said upright, to connect the inlet of the reactor to the walls of the channel so tight and thus limit leaks between the walls of the channel and the side faces of the reactor.

However, each side face of the UV reactor 100 has a diagonal opening, along the ultraviolet tubes 10, which divides it into two screens 26 and which allows the UV radiation from the lamps to reach a possible flow out of the reactor that the seals 221 n would not have prevented.

In addition, the presence of adjustable seals 221 and mostly solid side faces allows the flow to be channeled to the UV tube bundle 10 for optimal treatment.

Furthermore, to adapt to the height of water in the channel of a purification plant, a device for tilting the body of the UV reactor, resting on the civil engineering parts of said channel, makes it possible to adjust the tilt. of the reactor so as to adjust the height covered by the radiation from the lamps.

Due to the conditions of use of the UV reactor 100, the ultraviolet tubes 10 remain immersed for a prolonged period in waste water or other industrial effluents. Consequently, deposits of various kinds (dirt, lime, and other pollutants) form on the protective sheaths 12 enveloping the ultraviolet lamps 11.

The UV reactor cleaning system 100 makes it possible, according to an advantageous aspect of the invention, to automatically clean and maintain the sheaths 12 by a physical action and a chemical action, and for this purpose comprises cleaning rings provided with two sub parts: a powered sub part with a cleaning product and a photocatalytic medium in contact with the sheaths 12.

The cleaning system mainly comprises several cleaning assemblies 30 each comprising several cleaning rings 31 juxtaposed and assembled in a plate 32. Each cleaning assembly 30 is positioned in a row of ultraviolet tubes 10 and thus comprises as many rings 31 as there are. tubes 10 in said row, so that each ring 31 surrounds a tube 10. According to the illustrated embodiment, each row of tubes 10 is provided with two cleaning assemblies 30 spaced by a distance substantially equal to half the length of the tube. length of said row.

The cleaning system, consisting of the assemblies 30 and other elements described below, is mounted to slide in the oblique direction of the ultraviolet tubes 10. In fact, the tubes 10 represent guides in translation of the rings 31, the latter effecting a programmed reciprocating movement actuated by a motorized mechanism adapted so as to sweep the entire external surface of the tubes 10 subject to pollutant deposits.

Chemical cleaning

A suitable cleaning product, such as an acid, stored in a tank, not shown, placed in the auxiliary unit 50 is injected at the level of the protective sheaths 12 by means of a distribution circuit comprising a pipe 35, a network of 36 orifices and necessary fittings.

The orifices 36 thus make it possible to inject onto the sheaths 12 of the reactor the cleaning product which acts chemically on the outer surface of said sheaths to remove various deposits formed and prevent the formation of deposits during the operation of the cleaning system.

Physical cleaning

Each cleaning ring 31 comprises an internal support in contact with the external surfaces of the protective sheaths 12, on which a photocatalyst component is deposited to form the photocatalytic medium. The photocatalytic medium can be based on titanium dioxide and causes a reaction of degradation of pollutants under the effect of ultraviolet radiation.

As pointed out, the cleaning system is automated and can be triggered at regular intervals, after a determined operating time of the UV reactor, or in response to detection of an anomaly in the irradiance of UV radiation produced by UV lamps. To this end, the UV reactor can be fitted with UV radiation sensors placed in one or more sheaths and allowing the cleaning system to be triggered when the irradiance of the UV radiation captured falls below a certain threshold, due to the presence of unwanted deposits on the sheaths surrounding the ultraviolet lamps.

According to an advantageous aspect of the invention, the chemical cleaning and the physical cleaning take place simultaneously with high efficiency due in part to the movement of the cleaning system along the ultraviolet tubes 10.

Referring to Figure 3, the cleaning system is coupled to a geared motor 41, placed under a cover 42 of the electrical unit 40, which allows said system to be driven in a reciprocating motion along the tubes 10.

The auxiliary unit 50 may include, in addition to the cleaning product reservoir, other elements such as a product level indicator and an injection pump.

It emerges from the description of the present invention that additional elements, customary for a person skilled in the art, can be added to the UV reactor, and that certain elements of said reactor can be made differently without departing from the scope of the invention.

Claims

R E V E N D I C A T I O N S

1. Device (100) for treating fluid by ultraviolet radiation in the open channel of a wastewater treatment plant, comprising a plurality of ultraviolet tubes (10), each consisting of an ultraviolet lamp (11) placed in a sheath of protection (12), a body (20) in which said tubes are installed parallel to each other, a system for cleaning the protective sheaths, an electrical unit (40) and an auxiliary unit (50) containing a tank of cleaning product, characterized in that the ultraviolet tubes (10) are arranged inclined with respect to a horizontal direction of fluid flow, and in that the cleaning system comprises photocatalytic media in contact with the protective sleeves.

2. Device according to claim 1, wherein the body (20) has a parallelepipedal shape and comprises a base (21) extended along a longitudinal axis of the device, two uprights, an upstream upright (22a) and a downstream upright (22b) , perpendicular to the base, and two sides, each side comprising a pair of triangular plates (26) spaced apart, placed at two opposite angles of said side so as to define an opening parallel to the ultraviolet tubes (10).

3. Device according to claim 2, wherein each upright (22a, 22b) comprises two parallel and spaced bars defining openings corresponding to an inlet (E) of fluid at the level of the upstream upright (22a) and to an outlet (S). of fluid at the level of the downstream post (22b), the ultraviolet tubes (10) being entirely contained in a treatment volume delimited by said inlet and outlet and the base (21).

4. Device according to claim 3, wherein the upstream upright (22a) comprises two adjustable joints (221), each being placed along a bar of said upright, for sealingly connecting the inlet (E) and the walls. from the sewage treatment plant channel.

5. Device according to any one of the preceding claims, in which the ultraviolet lamps (11) are mercury vapor and produce monochromatic UV-C radiation, and in which the protective sleeves (12) are made of quartz.

6. Device according to any one of the preceding claims, in which the cleaning system comprises cleaning rings (31), each being placed around an ultraviolet tube (10) and provided with a part supplied by the product. cleaning agent and photocatalytic media.

7. Device according to claim 6, wherein the cleaning system comprises several cleaning assemblies (30), each of said assemblies comprising several cleaning rings (31) integral.

8. Device according to any one of the preceding claims, in which the photocatalytic media are composed in particular of titanium dioxide. 9. Device according to any one of the preceding claims, wherein the cleaning system is slidably mounted along the ultraviolet tubes (10) driven by a mechanism comprising a gear motor

(41). 10. Device according to any one of the preceding claims, wherein the body (20) further comprises gripping means (25) for lifting and moving said device.

11. Device according to any one of the preceding claims, wherein the inclination of the body (20) is adjustable by means bearing on a bottom of the sewage treatment plant channel so as to vary the height covered by the radiation. ultraviolet tubes (10), to match the height of the fluid in the channel.